Illuminated diver&#39;s slate

ABSTRACT

A reusable, illuminated diver&#39;&#39;s slate or writing tablet which utilizes a charge of chemiluminescent material. Light from the charge, preferably having wavelengths within a predetermined range, is directed through a light transmitting front wall, the surface of which is treated for writing. A mirrored rear wall increases efficiency of light use.

United States Patent [191 Naeseth et al.

[ Dec. 25, 1973 4/1959 Lieb 240/225 X ILLUMINATED DIVERS SLATE 2,883,770

5 [75] Inventors: Manley H. Naeseth, Panama City; 76987 5/1971 volght et 240/2 25 Herbert Larrimore, Lynn Haven, both of Primary ExaminerFred L. Braun [73] Assignee: The United States of America as Att0rney-Richard S. Sciascia et al.

represented by the Secretary of the Navy, Washington, DC.

22 F'] l 1973 l 1 Jan 57 ABSTRACT [211 App]. No.: 323,676

A reusable, illuminated divers slate or writing tablet [52] US. Cl. 240/2.25, 240/64 B which utilizes a charge of chemiluminescent material. [51] Int. Cl. F2lv 9/16 Light from the charge, preferably having wavelengths [581 Field of Search 240/2 LC, 2 E, 2.25, within a pred ter i d g is directed through 11 240/64 R, 6.4 B light transmitting front wall, the surface of which is treated for writing; A mirrored rear wall increases effi- [56] References Cited ciency of light use.

UNITED STATES PATENTS 3,215,453 11/1965 Malcom 240/6.4 B X 10 Claims, 3 Drawing Figures ILLUMINATED DIVERS SLATE STATEMENT OF GOVERNMENT INTEREST The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

FIELD OF THE INVENTION This invention relates to divers writing plates used for communication between divers, recording data, and the like. More particularly, the invention is directed to an improved divers slate which is illuminated by chemiluminescence.

DISCUSSION OF THE PRIOR ART Divers slates or writing tablets, used to pass information to or between divers, or used by divers to record information concerning their tasks, have been made in various forms. Among the most common forms presently in use are rigid plastic panels or slates which can be written upon with a grease pencil or crayon, or with common lead pencil if the panel surface is suitably roughened.

Self-illuminating plastic slates have been provided which comprise transparent or translucent plastic panelsin combination with a layer or lamination of a phosphorescent or otherwise luminescent material or compound which gives off visible light for a period of time after being excited by other light, for example, from an incandescent lamp. An example of the latter type of writing slate or tablet is described in U. S. Pat. No. 2,883,770 issued to Harry C. Lieb on Apr. 28, 1959. Luminous compounds, such as zinc sulphide phosphors or the like, which can be excited to luminance by exposure to light from an incandescent source, have the disadvantage of rapid decay of brightness or luminescence after the excitation is terminated. Accordingly, the use fulness of divers slates or tablets utilizing such materials is time limited. For example, typical slates using phosphorescent compounds and having been excited by a bright flashlight will provide only a low level of surface luminescence (on the order of 1.4 X foot lamberts) after 30 minutes have passed. Since most diving operations where data is being collected require substantially longer diving times than 30 minutes, it will be appreciated that slates or tablets of that type are inadequate.

It has been proposed that a radioactive material, such as those which are B emitting, be included with the phosphorescent compound to effect continued excitation thereof. This expedient provides a generally higher level of surface luminance and one which remains rela tively constant. However, it adds a potentially dangerous condition in that it subjects the user to an undesirable amount of radiation. Indeed, devices utilizing radioactive stimulated luminescence have been placed under governmental restrictions for the protection of the users.

SUMMARY OF THE INVENTION The present invention aims to overcome most or all of the aforementioned shortcomings of the prior art through the provision of a novel divers slate which makes use of chemiluminescent chemicals in liquid form as an illuminating agent.

In carrying out this invention, it is a principal object thereof to provide a divers slate which affords a higher degree of surface illumination than has been safely possible heretofore, and to do so without danger of exposure to radioactivity.

It is another object of the invention to provide a novel divers slate or tablet device which is selfilluminating, when charged with chemiluminescent liquid, to a useful degree of surface brightness for substantial periods of time, thereby affording a diver the convenience of being able to see the slate and any writing thereon throughout rather prolonged working periods.

As another object the invention aims to provide an improved self-illuminating diver's slate which avoids the inconvenience of having to subject a slate to a bright light for a period of time before use.

Yet another object is the provision of a diver's slate which realizes longterm economy in that it can be reused repeatedly by merely refilling with a charge of chemiluminescent liquid. In this regard, the basic device has an unlimited shelf life as opposed to prior phosphorescent slates which, while re-excitable a number of times within a given period, have a useful life normally limited to several years, after which the entire slate is discarded.

Other objects and many of the attendant advantages will be readily appreciated as the subject invention be comes better understood by reference to the following detailed description, when considered in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a front elevational view of a divers slate or writing tablet device embodying the invention;

FIG. 2 is a vertical sectional view of the device of FIG. 1, taken substantially along line 2-2 thereof; and

FIG. 3-is a sectional view taken substantially along line 3-3 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT In the form of the invention described hereinafter and illustrated in the drawings, there is provided a divers slate or writing tablet device, generally depicted at 10, which is particularly useful for conveying or recording information at an underwater location that does not have sufiicient natural or artificial illumination to permit a diver to read markings on a conventional divers slate. The device 10 comprises a generally rectangular, thin, flask having a front wall 12, a rear wall 14, side walls 16 and 18, a bottom wall 20, and a top wall 22. The mentioned walls are preferably formed of a material having light transmitting properties, sucli as glass, acrylic plastic, or the like. It is preferable that the light transmitting qualities be those of transparency although, as will be made apparent as the description proceeds, some or all of the surfaces of the walls of device. 10 are modified or treated to be otherwise than transparent. Also, as will presently appear, the light transmittance of the wall materials preferably favors certain wavelengths.

Located in one of the walls of device 10, preferably in top wall 22 of the preferred embodiment being described, is an opening 24 through which a chemiluminescent material can be introduced into cavity 26 defined by the aforementioned walls. Opening 24 is conveniently surrounded by a neck portion 28 which is adapted to receive a portion 30a of a stopper 30. in this embodiment, the interior of neck portion 28 is advantageously threaded to cooperate with mating threads on stopper portion 30a. A suitable gasket or washer 32, formed from rubber or a similar material, is provided between neck portion 28 and a head portion 30d of stopper 30. Additionally, stopper 30 is conveniently provided with a slot 300 for receiving a suitable tool to provide increased leverage for tightening or loosening thereof.

The outer surface 12a of front wall portion 12 is provided with a rough or matte finish which improves the ability thereof to receive pencil markings. This rough or matte finish may be achieved either by grinding or chemical etching, or by suitable coatings known to provide a frosting effect. Irrespective of the manner in which surface 120 is treated, it must remain in at least a translucent condition.

The outer surface of rear wall 14 carries a coating 34 which serves as a reflecting layer in the nature of a mirror, so that light traveling outwardly through wall 14 is redirected inwardly toward wall 12.

Cavity 26 is charged or filled with a light producing material 40, which material is of the type commonly referred to as chemiluminescent. Any known chemiluminescent material or composition maybe used in combination with device 10, which will provide a satisfactory level of illumination for a useful time period, and such a time period may be considered to be on the order of one to several hours for use in diving operations. Suitable chemiluminescence materials, which retain asmuch as 65 ft. lamberts of illumination ability after 30 minutes, and a useful level for periods reaching 2 hours, are sold commercially under the trademark CYALUME of the American Cyanimide Company,

Organic Chemicals Division, Boundbrook, New Jersey. Such materials are described in a number of patents, examples of which are U.S. Pat. Nos. 3,442,815 and 3,425,949. It will be understood, of course, that other chemiluminescent materials can be used in device 10.

At this point it should be noted that satisfactory illumination at an underwater, particularly ocean water, location is a function not only of mere brightness at the writing surface 1200f device 10, but also of the wavelength of the illuminating light. This is because ocean water absorbs and. scatters light of some wavelengths more than others. Stated conversely, some wavelengths of light are more effective at penetrating ocean water. The better penetration is achieved principally by blue light on the order of 0.40 to 0.50 a wavelength for offshore ocean water and by green to yellow light on the order of 0.50 to 0.58 p. wavelength for coastal waters.

The invention takes advantage of the foregoing by,

utilizing chemiluminescent materials having light emissions falling in the range of 0.40 to 0.58 n, and by forming walls 12 and 14 of material such as glass or plastic which has good light transmitting properties in the just mentioned range. This combination results in a divers slate device having optimum visibility characteristics due to minimization of scatter and absorption.

MODE OF OPERATION When it is desired to conduct a diving operation, during which divers, such as scuba divers, will be used to gather information, or during which it will be desirable for divers to communicate with one another concerning their task, one or more of the devices will be prepared by charging or filling with a chemiluminescent material through filler opening 24, which is then closed and sealed through the agency of stopper 30. The charges of chemiluminescent material, consisting of various compounds and agents, usually in the form of an oxalic component and a peroxide component are mixed just prior to use. Once mixed, the chemiluminescent material serves to emanate light energy which is normally directed outwardly in all directions therefrom. Some of such light energy travels directed through front wall 12, while another portion of such energy travels through rear wall 14 where it is reflected by mirror surface 34 for return through rear wall 14, chemiluminescent material 40, and front wall 12. The

combined light energy emanating from the device through front wall 12 thereof serves to provide a good contrast with any markings placed on roughened surface 12a of the front wall by a diver. Moreover, device 10 serves as a convenient source of illumination for other purposes such as illuminating an area of work or inspection by the divers.

After a dive is completed, device 10 is emptied of its charge of chemiluminescent material 40, rinsed, and then may be retained as a permanent record of the writings or markings thereon. Alternatively, such writings or markings may be erased, and device 10 recharged with fresh chemiluminescent material 40 just prior to a subsequent dive during which the device may be used.

Device 10 may be embellished with other refinements, such as the provision of lanyard means for attaching the device to the diver, and for attaching a writing instrument such as a pencil to the device.

It will be recognized that chemiluminescent material 40 is advantageously in the form of a substantially incompressible liquid so that device 10 can be used at substantial water depths and pressures without distortion or damage.

Obviously, other embodiments and modifications .of the subject invention will readily come to the mind of one skilled in the art having the benefit of the teachings presented in the foregoing description and the drawings. It is, therefore, to be understood that this invention is not to be limited thereto'and that said modifications and embodiments are intended to be includedwithin the scope of the appended claims.

What is claimed is: 1. A device for use by divers, comprising: flask means for containing a quantity of chemiluminescent material;

said flask means being characterized by a substan tially plane, light transmitting first wall having a surface capable of being written upon by a pencil, and a substantially plane, light transmitting second wall disposed in spaced, parallel relation to said first wall;

mirror means, disposed on said second wall, for reflecting light from chemiluminescent material, when such is contained in said flask means, through said first wall; and

chemiluminescent material filling said flask means.

2. A device as defined in claim 1, and wherein:

said first wall is substantially rectangular in plan and comprises a matte outer surface.

3. A device as defined in claim 2, and wherein:

said flask means comprises a portion defining an opening to the interior thereof; and

closure means for closing said opening with said chemiluminescent material within said mask means, said closure means being removable to permit removal and replacement of said chemiluminescent material.

4. A device as defined in claim 3, and wherein:

said light transmitting walls are formed of glass.

5. A device as defined in claim 4 and wherein:

said chemiluminescent material generates light energy having predominant wavelengths in a predetermined range; and

said light transmitting walls are characterized by ability to transmit light in said range.

6. A device as defined in claim 5, and wherein:

said predetermined range includes those wavelengths of light most readily transmitted by sea water.

7. A device as defined in claim 3, and wherein:

said light transmitting walls are formed of a rigid plastic material.

8. A device as defined in claim 7, and wherein:

said chemiluminescent material generates light energy having predominant wavelengths in a predetermined range; and

said light transmitting walls are characterized by ability to transmit light in said range.

9. A device as defined in claim 8, and wherein:

said predetermined range includes those wavelengths of light most readily transmitted by sea water.

10. A device for diver communication comprising in Combination:

a flask including rectangular plane parallel front and rear walls interconnected by side, bottom, and top walls, so as to definea cavity therebetween;

at least said front wall being light transmitting for light having wavelengths in the range of 0.40 to 0.58

a mirror surface associated with said rear wall and operative to reflect light toward said front wall; said front wall presenting an outer surface which is characterized as being rough, so as to accept markings by a common lead pencil;

' an opening through one of said walls for introducing material into, and removing material from, said cavity;

stopper means for closing said opening;

a quantity of light generating, chemiluminescent material filling said cavity; and

said chemiluminescent material being active to generate light having predominant wavelengths within said range. 

1. A device for use by divers, comprising: flask means for containing a quantity of chemiluminescent material; said flask means being characterized by a substantially plane, light transmitting first wall having a surface capable of being written upon by a pencil, and a substantially plane, light transmitting second wall disposed in spaced, parallel relation to said first wall; mirror means, disposed on said second wall, for reflecting light from chemiluminescent material, when such is contained in said flask means, through said first wall; and chemiluminescent material filling said flask means.
 2. A device as defined in claim 1, and wherein: said first wall is substantially rectangular in plan and comprises a matte outer surface.
 3. A device as defined in claim 2, and wherein: said flask means comprises a portion defining an opening to the interior thereof; and closure means for closing said opening with said chemiluminescent material within said mask means, said closure means being removable to permit removal and replacement of said chemiluminescent material.
 4. A device as defined in claim 3, and wherein: said light transmitting walls are formed of glass.
 5. A device as defined in claim 4 and wherein: said chemiluminescent material generates light energy having predominant wavelengths in a predetermined range; and said light transmitting walls are characterized by ability to transmit light in said range.
 6. A device as defined in claim 5, and wherein: said predetermined range includes those wavelengths of light most readily transmitted by sea water.
 7. A device as defined in claim 3, and wherein: said light transmitting walls are formed of a rigid plastic material.
 8. A device as defined in claim 7, and wherein: said chemiluminescent material generates light energy having predominant wavelengths in a predetermined range; and said light transmitting walls are characterized by ability to transmit light in said range.
 9. A device as defined in claim 8, and wherein: said predetermined range includes those wavelengths of light most readily transmitted by sea water.
 10. A device for diver communication comprising in combination: a flask including rectangular plane parallel front and rear walls interconnected by side, bottom, and top walls, so as to define a cavity therebetween; at least said front wall being light transmitting for light having wavelengths in the range of 0.40 to 0.58 Mu ; a mirror surface associated with said rear wall and operative to reflect light toward said front waLl; said front wall presenting an outer surface which is characterized as being rough, so as to accept markings by a common lead pencil; an opening through one of said walls for introducing material into, and removing material from, said cavity; stopper means for closing said opening; a quantity of light generating, chemiluminescent material filling said cavity; and said chemiluminescent material being active to generate light having predominant wavelengths within said range. 